Chlordane persistence

Chlordane is readily absorbed by warm-blooded animals through skin, diet, and inhalation. It is quickly distributed in the body and tends to concentrate in liver and fat (WHO 1984). Up to 75% of a single oral dose of chlordane administered to rats and mice was absorbed in the gut, and up to 76% of an aerosol dose was absorbed in the respiratory tract (Nomeir and Hajjar 1987). Rabbits absorbed 33% in the gut following oral administration (USEPA 1988). Chlordane residues in mammals were usually not measurable 4 to 8 weeks after cessation of exposure (Ingle 1965). Chlordane persistence in human serum and whole body was estimated at 88 days and 21 days, respectively this compares to a Tb 1/2 of about 23 days in rats fed chlordane for 56 days (USEPA 1980). 

Pesticides are also a major source of concern as water and soil pollutants. Because of their stability and persistence, the most hazardous pesticides are the organochlorine compounds such as DDT, aldrin, dieldrin, and chlordane. Persistent pesticides can accumulate in food chains for example, shrimp and fish can concentrate some pesticides as much as 1000- to 10,000-fold. This bioaccumulation has been well documented with the pesticide DDT, which is now banned in many parts of the world. In contrast to the persistent insecticides, the organophosphorus (OP) pesticides, such as malathion, and the carbamates, such as carbaryl, are short-lived and generally persist for only a few weeks to a few months. Thus these compounds do not usually present as serious a problem as the earlier insecticides. Herbicides, because of the large quantity used, are also of concern as potential toxic pollutants. Pesticides are discussed in more detail in Chapter 5. 

The oncogenicity concerns with chlordane persisted until Velsicol and EPA negotiated a voluntary cancellation of most of the termiticide uses in 1987 and avoided a cancellation hearing. The cancellation hearing was expected to be hard fought, as the evidence of carcinogenicity was based on mouse liver tumors, which provided evidence of a very different weight in 1987 than in 1979. 

Chlordane residues in mammals were usually not measurable 4-8 weeks after cessation of exposure. Chlordane persistence in human serum and whole body was estimated at 88 and 21 days, respectively this compares to a Tbl/2 of about 23 days in rats fed chlordane for 56 days. 

Ritter L, Solomon KR (1995) A review of the persistent organic pollutants DDT, aldrin, dieldrin, endrin, chlordane, heptachlor, hexachlorobenzene, mirex, toxaphene, polychlorinated biphenyls, dioxins and furans. In T.I.P.o.C.S. (IPCS) (ed) Geneve, Suisse... 

Chlordanes and their metabolites are ubiquitous in the environment at low concentrations, but at a high occurrence in samples analyzed. Atmospheric transport is considered to be the major route of global dissemination. Some chlordane isomers persist in soils for 3 to 15 years, although there seems to be little accumulation of chlordanes by crop plants grown in these soils. Lengthy persistence of various chlordane isomers, especially m-chlordane and trans-nonachlor, has been reported in certain organisms, but this has varied greatly between species and tissues. 

Chlordane has been detected in both groundwater and surface water at low levels of 0.001 to 0.01 pg/L (USEPA 1988). A high frequency of chlordane detection was noted in seawater samples collected from a Hawaiian marina up to 90% of all samples contained cw-chlordane, and 68% contained trans-chlordane (IARC 1979). Because of chlordane s use as a soil-injected insecticide and its persistence, it has the potential to contaminate groundwater, particularly when it is applied near existing wells (USEPA 1988). 

Chlordane residue data for amphibians and reptiles are extremely limited. Maximum concentrations of chlordane isomers did not exceed 70 pg/kg FW of oxychlordane in eggs of the American crocodile, Crocodylus acutus, or 250 pg/kg FW in carcass of the common garter snake, Thamnophis sirtalis (Table 13.2). However, California newts, Tarichia torosa, taken near a lake treated with 10 pg/L technical chlordane had greatly elevated chlordane residues in liver and comparatively low concentrations in carcass, stomach, and stomach contents. After 14 days, livers contained about 34 mg/kg total chlordanes lipid weight — about 19% chlordanes, 9% nonachlors, and 6% chlor-denes (Albright et al. 1980). After 2.8 years, 98% of the total chlordanes was lost. 7ra .v-nonachlor was the most persistent component in newt liver, accounting for up to 55% of the total chlordanes in specimens collected 2.8 years after application (Table 13.2) (Albright et al. 1980). 

Concern for the continued widespread use of chlordane centers on its ability to cause liver cancer in domestic mice. Other adverse effects in mammals, such as elevated tissue residues and growth inhibition, were frequently associated with diets containing between 0.76 and 5.0 mg chlordane/kg feed. Metabolism of technical chlordane by mammals results primarily in oxychlordane, a metabolite that is about 20 times more toxic than the parent compound and the most persistent metabolite stored in adipose tissues. Chlordane interactions with other agricultural chemicals produced significant biological effects in warm-blooded organisms, indicating a need for additional research on this subject. 

Residues of dv-chlordanc were preferentially stored and magnified over tran.v-chlordane by freshwater fish and invertebrates in ponds treated with technical chlordane at concentrations up to 1.14 pg/L. The di-isomer, with an estimated Tb 1/2 of 46 days, persisted longer than did the trans-isomer (Johnson and Finley 1980). Tissue concentrations of 106,000 pg total chlordanes/kg, on a lipid weight basis, were associated with reduced survival of estuarine invertebrates (Zitko 1978). Moribund amphipods (Hyallela azteca), for example, contained 137,000 to 2,180,000 pg/kg lipid of various chlordanes, heptachlors, and chlordenes (Zitko 1978). In fish, chlordane concentrations of 300,000 to 4,000,000 pg/kg lipid weight in tissues were lethal (Zitko 1978). 

The lethal effect of technical chlordane in birds is attributed primarily to chlordane metabolites, especially oxychlordane and, to a lesser extent, heptachlor epoxide (Shekel et al. 1983). Oxychlor-dane was the most persistent chlordane component in avian brain tissues. The half-time persistence of oxychlordane in brain was 63 days, and 95% loss was estimated in 280 days. The Tb 1/2 for heptachlor epoxide was 29 days, and for /ran.v-nonachlor it was 19 days (Shekel et al. 1979). Oxychlordane residues in brain tissue approaching 5 mg/kg FW were considered within the lethal hazard zone to birds (Shekel et al. 1979). 

The half-life of chlordane in water is comparatively short. m-Chlordane, for example, usually persists less than 18 h in solution. In soils, however, some chlordane isomers persist for 3 to 14 years because of low solubility in water, high solubility in lipids, and relatively low vapor pressure. There seems to be little accumulation of chlordane in crops grown in contaminated soils. 

Chlordane is readily absorbed by warm-blooded animals via skin, diet, and inhalation, and distributed throughout the body. In general, residues of chlordane and its metabolites are not measurable in tissues 4 to 8 weeks after exposure, although metabolism rates varied significantly between species. Food chain biomagnification is usually low, except in some marine mammals. In most mammals, the metabolite oxychlordane has proven much more toxic and persistent than the parent chemical. 

Estimated half-lives for chlorinated hydrocarbon pesticides vary widely [16, 22] Aldrin, 1-9 Dieldrin, 3-7 Chlordane, 1-8 Heptachlor, 1-4 and DDT, 3-10 years. Half-lives for PCBs range from one year to 16 years [23]. Other types of pesticides, e.g. organophosphates, triazines, carbamates and ureas, are generally less persistent [16, 24],... 

That some chemicals persist for long periods has been recognized for many years. Most of the pesticidal chemicals that came into wide use in the 1930s and 1940s were chlorinated organic compounds such as DDT, dieldrin, chlordane, kepone, toxaphene, and several others. 

Soil The actinomycete Nocardiopsis sp. isolated from soil extensively degraded pure cis- and /ra/3s-chlordane to dichlorochlordene, oxychlordane, heptachlor, heptachlor e/ c/o-epoxide, chlordene chlorohydrin, and 3-hydroxy-traas-chlordane. Oxychlordane slowly degraded to 1-hydroxy-2-chlorochlordene (Beeman and Matsumura, 1981). In Hudson River, NY sediments, the presence of adsorbed chlordane suggests it is very persistent in this environment (Bopp et al., 1982). The reported half-life in soil is approximately 1 yr (Hartley and Kidd, 1987). 

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